This project is devoted to research in clinical hypertension. The role of the renin-angiotensin system will be studied through measurement of plasma renin activity, plasma renin substrate and hemodynamic response to the infusion of a specific angiotension II antagonist, saralasin. In addition, the interaction of the sympathetic nervous system in clinical hypertension will be assessed by measurement of plasma catecholamines and by studying the hemodynamic response to specific alpha and beta receptor blockade.